SA1 experienced sustained negative pricing at –$20/MWh during the 00:50 interval on 19 August 2026, with three intervals at –$8/MWh in the preceding half-hour. The region was oversupplied with renewable generation (1,136 MW wind and 471 MW solar combined) during a low-demand overnight period, with minimal dispatchable load available to absorb the surplus.
The negative prices reflect structural oversupply: high wind and solar output coinciding with night-time minimum demand, forcing the system to pay participants to reduce generation. Binding constraints with significant marginal values, particularly the constraint with $963.60/MWh marginal value, indicate active transmission limitations preventing efficient export of excess renewable energy from SA1, forcing local prices into negative territory as the market cleared at the lowest cost that still satisfied binding constraint limits.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.